A Pwr Assembly Computational Scheme Based on the Dragon V4 Lattice Code

This paper describes the validation of a two-level computational scheme dedicated to PWR assembly calculations within the framework of the DRAGON v4 lattice code. The first level uses the interface current method for both the subgroup-based self-shielding and main flux calculation, with a 172-group XMAS energy discretization. The second level uses the method of characteristics preconditioned with the algebraic collapsing acceleration technique, posterior to the condensation of the material properties with a representative weighting flux obtained from the first level. This two-level scheme is compared to both a reference single-level computational scheme with the method of characteristics and to a Monte-Carlo calculation on a zero-burnup benchmark. The numerical results obtained with both twoand one-level computational schemes are in very good agreement with the Monte-Carlo calculation. Moreover, the deviation of the two-level scheme with respect to the one-level scheme is assessed when depletion is considered and is found to be small.